Cell necrosis apparatus and method

ABSTRACT

A cell necrosis apparatus includes an introducer with a distal end sufficiently sharp to penetrate tissue, an energy delivery including a plurality of electrodes and a slidable sensing member. Each electrode of the plurality of electrodes has a tissue piercing distal end and is positionable in the introducer as the introducer is advanced through tissue. At least one electrode of the plurality of electrodes is deployable with curvature from the introducer. The slidable sensing member is positionable within the introducer and electrically coupled to the energy delivery device. The sensing member is configured to measure a property of the energy delivery device or at least one electrode of the plurality of electrodes.

REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.09/148,571, filed Sep. 4, 1998 which is a continuation-in-partapplication of Ser. No. 09/047,845, filed Mar. 25, 1998, which is acontinuation-in-part of Ser. No. 09/020,182, filed Feb. 6, 1998, whichis a continuation-in-part of Ser. No. 08/963,239, filed Nov. 3, 1997,which is a continuation-in-part of Ser. No. 08/515,379, filed Aug. 15,1995, all incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates generally to a cell necrosis apparatus,and more particularly to a cell necrosis apparatus with an introducerand deployable electrodes.

[0004] 2. Description of the Related Art

[0005] Current open procedures for treatment of tumors are extremelydisruptive and cause a great deal of damage to healthy tissue. Duringthe surgical procedure, the physician must exercise care in not cuttingthe tumor in a manor that creates seeding of the tumor, resulting inmetastasis. In recent years, development of products has been directedwith an emphasis on minimizing the traumatic nature of traditionalsurgical procedures.

[0006] There has been a relatively significant amount of activity in thearea of hyperthermia as a tool for treatment of tumors. It is known thatelevating the temperature of tumors is helpful in the treatment andmanagement of cancerous tissues. The mechanisms of selective cancer celleradication by hyperthermia are not completely understood. However, fourcellular effects of hyperthermia on cancerous tissue have been proposed,(i) changes in cell or nuclear membrane permeability or fluidity, (ii)cytoplasmic lysomal disintegration, causing release of digestiveenzymes, (iii) protein thermal damage affecting cell respiration and thesynthesis of DNA or RNA and (iv) potential excitation of immunologicsystems. Treatment methods for applying heat to tumors include the useof direct contact radio-frequency (RF) applicators, microwave radiation,inductively coupled RF fields, ultrasound, and a variety of simplethermal conduction techniques.

[0007] Among the problems associated with all of these procedures is therequirement that highly localized heat be produced at depths of severalcentimeters beneath the surface of the skin.

[0008] Attempts to use interstitial local hyperthermia have not provento be very successful. Results have often produced nonuniformtemperatures throughout the tumor. It is believed that tumor massreduction by hyperthermia is related to thermal dose. Thermal dose isthe minimum effective temperature applied throughout the tumor mass fora defined period of time. Because blood flow is the major mechanism ofheat loss for tumors being heated, and blood flow varies throughout thetumor, more even heating of tumor tissue is needed to ensure effectivetreatment.

[0009] The same is true for ablation of the tumor itself through the useof RF energy. Different methods have been utilized for the RF ablationof masses such as tumors. Instead of heating the tumor it is ablatedthrough the application of energy. This process has been difficult toachieve due to a variety of factors including, (i) positioning of the RFablation electrodes to effectively ablate all of the mass, (ii)introduction of the RF ablation electrodes to the tumor site and (iii)controlled delivery and monitoring of RF energy to achieve successfulablation without damage to non-tumor tissue.

[0010] Thus, non-invasive procedures for providing heat to internaltissue have had difficulties in achieving substantial specific andselective treatment.

[0011] Examples illustrating the use of electromagnetic energy to ablatetissue are disclosed in: U.S. Pat. No. 4,562,200; U.S. Pat. No.4,411,266; U.S. Pat. No. 4,838,265; U.S. Pat. No. 5,403,311; U.S. Pat.No. 4,011,872; U.S. Pat. No. 5,385,544; and U.S. Pat. No. 5,385,544.

[0012] There is a need for a cell necrosis apparatus with at least twoelectrodes that are deployable with curvature from an introducer. Thereis another need for a cell necrosis apparatus with at least twoelectrodes that are selectably deployable with curvature from anintroducer to a desired deployed geometric configuration. There is yet afurther need for a cell necrosis apparatus that provides deployableelectrodes that create a variety of different geometric cell necrosislesions.

SUMMARY OF THE INVENTION

[0013] Accordingly, an object of the invention is to provide a cellnecrosis apparatus that provides tissue reduction at selected anatomicalsites.

[0014] Another object of the invention is to provide a treatmentapparatus to create cell necrosis.

[0015] Still another object of the invention is to provide a cellnecrosis apparatus that has at least two electrodes which are deployablefrom an introducer with curvature and a third electrode which isdeployable with minimal curvature.

[0016] Yet another object of the invention is to provide a cell necrosisapparatus with selectively deployed electrodes.

[0017] A further object of the invention is to provide a cell necrosisapparatus that is configured to deploy electrodes selectively at atissue site to create a desired cell necrosis lesion.

[0018] These and other objects of the invention are achieved in a cellnecrosis apparatus including an introducer with a distal endsufficiently sharp to penetrate tissue, an energy delivery including aplurality of electrodes and a slidable sensing member. Each electrode ofthe plurality of electrodes has a tissue piercing distal end and ispositionable in the introducer as the introducer is advanced throughtissue. At least one electrode of the plurality of electrodes isdeployable with curvature from the introducer. The slidable sensingmember is positionable within the introducer and electrically coupled tothe energy delivery device. The sensing member is configured to measurea property of the energy delivery device or at least one electrode ofthe plurality of electrodes.

[0019] In another embodiment, a cell necrosis apparatus has an energydelivery device that includes a first RF electrode with a tissuepiercing distal portion and a second RF electrode with a tissue piercingdistal portion. The first and second RF electrodes are positionable inthe introducer as the introducer is advanced through tissue anddeployable with curvature from the introducer at a selected tissue site.A groundpad electrode is coupled to the first and second RF electrodes.A first sensor is coupled to the groundpad electrode.

BRIEF DESCRIPTION OF THE FIGURES

[0020]FIG. 1 is cross-sectional view of a cell necrosis apparatus of thepresent invention with two deployable electrodes and an deployablemember at a selected cell necrosis tissue site.

[0021]FIG. 2(a) illustrates a cross-sectional view of an embodiment of acell necrosis apparatus of the present invention with a first and asecond set of deployable electrodes.

[0022]FIG. 2(b) illustrates the cell necrosis apparatus of FIG. 2(a)positioned at a targeted cell necrosis tissue site.

[0023]FIG. 3 illustrates an embodiment of a cell necrosis apparatus ofthe present invention with multiple sensors coupled to electrodes.

[0024]FIG. 4 illustrates a spherical cross-section of an electrodeutilized with a cell necrosis apparatus of the present invention.

[0025]FIG. 5 illustrates an elliptical cross-section of an electrodeutilized with a cell necrosis apparatus of the present invention.

[0026]FIG. 6 illustrates a cross-section of an electrode utilized with acell necrosis apparatus of the present invention with a largercross-sectional length than its width.

[0027]FIG. 7 illustrates a cross-section of an electrode utilized with acell necrosis apparatus of the present invention with a flat-likeexternal surface.

[0028]FIG. 8 is a perspective view of a cell necrosis apparatus of thepresent invention that includes insulation sleeves positioned atexterior surfaces of the electrodes.

[0029]FIG. 9 is a perspective view of a cell necrosis apparatus of thepresent invention that includes multiple insulation sleeves thatcircumferentially insulate selected sections of the electrodes.

[0030]FIG. 10 is a perspective view of a cell necrosis apparatus of thepresent invention with insulation that extends along longitudinalsections of the electrodes to define adjacent longitudinal energydelivery surfaces.

[0031]FIG. 11 is a cross-sectional view of the cell necrosis apparatusof FIG. 10 taken along the lines 11-11.

[0032]FIG. 12 is a perspective view of a cell necrosis apparatus of thepresent invention with insulation that extends along longitudinalsections of the electrodes and does not continue to distal ends of theelectrodes.

[0033]FIG. 13 is a cross-sectional view illustrating the positioning ofelectrodes adjacent to a selected tissue site with insulation thatextends along a longitudinal surface of the electrodes and theinsulation faces away from a central axis of the selected tissue site.

[0034]FIG. 14 is a cross-sectional view illustrating the positioning ofelectrodes at a selected tissue site with insulation that extends alonga longitudinal surface of the electrodes and the insulation faces towarda central axis of the selected tissue site.

[0035]FIG. 15 is a close-up perspective view of a surface area of anelectrode body at a distal end of an electrode of a cell necrosisapparatus of the present invention.

[0036]FIG. 16 is a perspective view of a cell necrosis apparatus of thepresent invention with spacers associated with each deployed electrode.

[0037]FIG. 17 is a cross-sectional view of a cell necrosis apparatus ofthe present invention illustrating a spacer, an associated electrode andinsulation inside the spacer.

[0038]FIG. 18 is a cross-sectional view of an embodiment of a cellnecrosis apparatus of the present invention that includes a slidablemember that engages a power source to a contact coupled to theelectrodes.

[0039]FIG. 19 is a cross-sectional view of the apparatus of FIG. 18 withthe slidable member pulled back and disengaging the power source fromthe electrodes.

[0040]FIG. 20 is a block diagram illustrating the inclusion of acontroller, electromagnetic energy source and other electroniccomponents of the present invention.

[0041]FIG. 21 is a block diagram illustrating an analog amplifier,analog multiplexer and microprocessor used with the present invention.

DETAILED DESCRIPTION

[0042] Referring to FIG. 1, one embodiment of a cell necrosis apparatus10 includes an introducer 12 with a distal end 14 sufficiently sharp topenetrate tissue. An energy delivery device, generally denoted as 16,includes a first RF electrode 18 and a second RF electrode 20.Electrodes 18 and 20 are positionable in introducer 12 as introducer 12advances through tissue. Electrodes 18 and 20 have tissue piercingdistal ends 22 and 24, respectively. Electrodes 18 and 20 are selectablydeployed with curvature from a distal end 14 or a side port formed in adistal portion 26 of introducer 12 to a selected tissue site 28. Tissuesite 28 can be any tissue mass and can be a tumor to be ablated.Electrodes 18 and 20 are selectably deployed to be controllablypositioned at a desired location relative to tissue site 28 thatincludes internal placement, external placement at a periphery of tissuesite 28 and at any desired location relative to tissue site 28. Theselectable deployment of electrodes 18 and 20 can be achieved with theamount of advancement of electrodes 18 and 20 from introducer 12,independent advancement of electrodes 18 and 20 from introducer 12, thelengths and/or sizes of energy delivery surfaces of electrodes 18 and20, the variation in materials used for electrodes 18 and 20 as well asvariation of geometric configuration of electrodes 18 and 20 in theirdeployed states.

[0043] Electrodes 18 and 20 are in compacted positions while they arepositioned in introducer 12. As electrodes 18 and 20 are advanced fromintroducer 12 they move to a deployed state from their compactedconfigurations. Any number of electrodes can be included in energydelivery device 16. The electrodes of energy delivery device 16 can bedeployed simultaneously, in pairs, in sets and one at a time. Anelectrode advancement member 30 is coupled to energy delivery device 16.Electrode advancement member 30 can be actuated by the physician bymovement of a proximal end 32 relative to a longitudinal axis ofintroducer 12.

[0044] Introducer 12 can be flexible. In one embodiment, introducer 12is sufficiently flexible to pierce tissue, and move in any desireddirection through tissue to tissue site 28. In another embodiment,introducer 12 is sufficiently flexible to reverse its direction oftravel and move in direction back upon itself. In one embodiment,introducer 12 is more flexible than electrodes 18 and 20.

[0045] When introducer 12 reaches tissue site 28, including but notlimited to a solid lesion, energy delivery device 16 is deployedpreferably from distal end 14 of introducer 12. Energy delivery device16 can also be deployed from side ports formed in the body of introducer12. In the deployed state energy delivery device 16 becomes expandedfrom its compacted configuration in introducer 12 and is selectivelypositioned relative to tissue site 12. Electrodes 18 and 20 can beportioned within an interior of tissue site 12, at the exterior oftissue site 12 as well as combinations thereof. Electrodes 18, 20 aswell as third, fourth, fifth, etc. electrodes are advanceable differentlengths from distal end 14 of introducer 12. In one embodiment, theelectrodes of deployed energy delivery device 16 are positioned equallydistant a central axis of tissue site 28. Volumetric cell necrosis canproceed from the interior, exterior of tissue site 28 as well as variouscombinations thereof with each deployed electrode of energy deliverydevice 16 in order to create a selectable and predictable cell necrosis.

[0046] Electrodes 18 and 20 can be made of a variety of conductivematerials, both metallic and non-metallic. One suitable material is type304 stainless steel of hypodermic quality. In some applications, all ora portion of electrodes 18 and 20 can be made of a shaped memory metal,such as NiTi, commercially available from Raychem Corporation, MenloPark, Calif. A radiopaque marker 21 can be coated on electrodes 18 and20 for visualization purposes.

[0047] Electrodes 18 and 20 can have different lengths that are advancedfrom distal end 14 of introducer 12. The lengths can be determined bythe actual physical length of electrodes 18 and 20, the length of anenergy delivery surface of electrodes 18 and 20 and the length ofelectrodes 18 and 20 that is not covered by an insulator. Suitablelengths include but are not limited to 17.5 cm, 25.0 cm. and 30.0 cm.The actual lengths of electrodes 18 and 20 depends on the location oftissue site 28 to be ablated, its distance from the skin, itsaccessibility as well as whether or not the physician chooses alaparoscopic, percutaneous or other procedure.

[0048] A deployable member 34 can be coupled to electrode advancementmember 30. Deployable member 34 can provide a variety of differentfunctions including but not limited to the placement of a sensor at aselected tissue site to measure/monitor temperature and/or impedance.Additionally, all or a portion of deployable member 34 can be an RFelectrode operable in bi-polar or mono-polar modes. Deployable member 34can also be a groundpad electrode.

[0049] A sensor 36 can be coupled to deployable member 34 at a distalend 38, or at any physical location of deployable member 34. In thismanner, temperature and/or impedance is measured or monitored at adistal portion of tissue site 28 or at any position in or external totissue site 28. Deployable member 34 is deployable from distal end 14 ofintroducer 12 with less curvature than electrodes 18 and 20. Deployablemember 34 can be deployable from distal end 14 without substantially anycurvature.

[0050] Sensor 36 permits accurate measurement of temperature at tissuesite 28 in order to determine, (i) the extent of cell necrosis, (ii) theamount of cell necrosis, (iii) whether or not further cell necrosis isneeded and (iv) the boundary or periphery of the ablated mass. Further,sensor 36 reduces non-targeted tissue from being destroyed or ablated.

[0051] Sensor 36 is of conventional design, including but not limited tothermistors, thermocouples, resistive wires, and the like. A suitablethermal sensor 36 includes a T type thermocouple with copperconstantene, J type, E type, K type, fiber optics, resistive wires,thermocouple IR detectors, and the like. It will be appreciated thatsensor 36 need not be a thermal sensor.

[0052] Sensor 36 measures temperature and/or impedance to permitmonitoring and a desired level of cell necrosis to be achieved withoutdestroying too much tissue. This reduces damage to tissue surroundingthe targeted mass to be ablated. By monitoring the temperature atvarious points within and outside of the interior of tissue site 28, adetermination of the selected tissue mass periphery can be made, as wellas a determination of when cell necrosis is complete. If at any timesensor 36 determines that a desired cell necrosis temperature isexceeded, then an appropriate feedback signal is received at an energysource 40 coupled to energy delivery device 16 which then regulates theamount of electromagnetic energy delivered to electrodes 18 and 20.

[0053] Energy source 40 can be an RF power supply, an ultrasound energysource, a microwave generator, a resistive heating source, a laser andthe like. Microwave antenna, optical fibers, resistive heating elementsand ultrasound transducers can be substituted for electrodes 18 and 20.When energy source 40 is an RF power supply, 5 to 200 watts, preferably5 to 100, and still more preferably 5 to 50 watts of electromagneticenergy is delivered from energy source 40 to the electrodes of energydelivery device 16 without impeding out the electrodes.

[0054] Electrodes 18 and 20 are electromagnetically coupled to energysource 40. The coupling can be direct from energy source 40 to eachelectrode 18 and 20 respectively, or indirect by using a collet, sleeveand the like which couples one or more electrodes to energy source 40.

[0055] Referring now to FIG. 2(a), another embodiment of apparatus 10 isshown. Apparatus 10 includes a first set 42 of RF electrodes and asecond set 44 of RF electrodes. First and second sets 42 and 44 caninclude one, two, three, four, five, etc, number of RF electrodes. Asillustrated in FIG. 2, first set 42 includes electrodes 46 and 48, andsecond set 44 includes electrodes 50 and 52. It will be appreciated thatfirst and second sets 42 and 44 can include more or less electrodes thanare illustrated in FIG. 2. Electrodes 46, 48, 50 and 52 have tissuepiercing distal ends, are positionable in introducer 12 in compactedstates, and advanceable to deployed states from distal end 14 withcurvature from introducer 12. First set 42 is deployable a greaterdistance from distal end 14 than second set 44.

[0056] First and second sets 42 and 44 are coupled to electrodeadvancement member 30 and can be simultaneously or individually deployedfrom distal end 14. Optionally coupled to first set 42, second set 44and/or electrode advancement member 30 is deployable member 34. Again,deployable member 34 can be coupled to a sensor 36 and all or a portionof deployable member 34 may be an RF electrode.

[0057]FIG. 2(b) illustrates the use of multiple sensors 36. Sensors 36can be coupled to all or some of electrodes 46, 48, 50 and/or 52 atdifferent positions of the electrodes. In various embodiments, sensorsare positioned at distal ends of electrodes 46 through 52, at positionsthat are adjacent to distal end 14 of introducer 12, and at sites thatare somewhere intermediate between the distal and proximal portions ofdeployed lengths of the electrodes. Deployable member 34 can includesensors at distal and proximal portions of its deployed length in tissuesite 28. The placement of sensors 36 at different locations provides ameasurement of temperature and/or impedance, and a determination of thelevel of cell necrosis, created at tissue site 28.

[0058] As shown in FIG. 3, electrodes 18, 20, 46, 48, 50 and 52,collectively “electrodes 18”, can each be coupled to one or more sensors36. Sensors 36 can be at exterior surfaces of electrodes 18 at theirdistal ends, intermediate sections as well as adjacent to distal end 14of introducer 12. Some or all of electrodes 18 and deployable member 34may have a hollow lumen by which a variety of different fluidic mediumcan be introduced from proximal to distal ends. Suitable fluidic mediainclude but are not limited to electrolytic solutions, chemotherapeuticagents, drugs, medicaments, gene therapy agents, contrast agents and thelike.

[0059] Electrode 18, as well as deployable member 34, can have a varietyof different geometric cross-sections. Electrodes 18 can be made ofconductive solid or hollow straight wires of various shapes such asround, flat, triangular, rectangular, hexagonal, elliptical and thelike. FIGS. 4 and 5 illustrate circular and elliptical cross-sections.In FIG. 6, the cross-section has a greater length “L” than a width of“W”. If FIG. 7, the cross-sectional is elongated. In variousembodiments, the cross-sectional has a greater length than a width inorder to enhance ultrasonic viewability.

[0060] Each, a portion of all electrodes 18, as well as deployablemember 34, have an exterior surface that is wholly or partiallyinsulated and provide a non-insulated area which is an energy deliverysurface. In FIG. 8, two electrodes 18 include insulation 54. In theembodiment of FIG. 8, insulation 54 is a sleeve that can be fixed oradjustable. The active area of electrodes 18 is non-insulated andprovides an energy delivery surface 56.

[0061] In the embodiment illustrated in FIG. 9, insulation 54 is formedat the exterior of electrodes 18 in circumferential patterns, leaving aplurality of energy delivery surfaces 56. Referring now to theembodiment of FIGS. 10 and 11, insulation 54 extends along alongitudinal exterior surface of electrodes 18. Insulation 54 can extendalong a selected distance along a longitudinal length of electrodes 18and around a selectable portion of a circumference of electrodes 18. Invarious embodiments, sections of electrodes 18 can have insulation 54along selected longitudinal lengths of electrodes 18 as well ascompletely surround one or more circumferential sections of electrodes18. Insulation 54 positioned at the exterior of electrodes 18 can bevaried to define any desired shape, size and geometric energy deliverysurface 56.

[0062] In FIG. 12, insulation 54 is disposed on only one section of adeployed length of electrodes 18. Energy delivery surfaces 56 are atdistal portions of electrodes 18 as well as on longitudinal surfacesadjacent to insulation 54. In FIG. 13, insulation 54 extends along alongitudinal length of electrodes 18 can face toward a central axis 58of tissue site 28 and energy delivery surface 56 faces towards in adirection toward the central axis 58. In FIG. 14, insulation 54 extendsalong a longitudinal length of electrodes 18 and faces away from centralaxis 58 with energy delivery surface 56 facing away from central axis58. In the embodiments illustrated in FIGS. 12 and 13, three electrodes18 are positioned inside or outside of a periphery of tissue site 28. Itwill be appreciated that any number of electrodes 18 can be deployedwith and without insulation to created a selectable cell necrosispattern.

[0063] Electrodes 18 are selectably deployable from introducer 12 withcurvature to create any desired geometric area of cell necrosis. Theselectable deployment is achieved by having electrodes 18 with, (i)different advancement lengths from introducer 12, (ii) differentdeployed geometric configurations, (iii) variations in cross-sectionalgeometries, (iv) selectable insulation provided at each and/or all ofthe deployed electrodes 18, or (v) the use of adjustable insulation.

[0064] Deployed electrodes 18 can create a variety of differentgeometric cell necrosis zones including but not limited to spherical,semi-spherical, spheroid, triangular, semi-triangular, square,semi-square, rectangular, semi-rectangular, conical, semi-conical,quadrilateral, semi-quadrilateral, semi-quadrilateral, rhomboidal,semi-rhomboidal, trapezoidal, semi-trapezoidal, combinations of thepreceding, geometries with non-planar sections or sides, free-form andthe like.

[0065] In one embodiment, the ultrasonic visibility of electrodes 18through is enhanced by creating a larger electrode distal end surfacearea 60. Surface area 60 is the amount of the electrode body that is atthe distal end of electrodes 18. Referring now to FIG. 15 the distal endof electrode 18 has at cut angle of at least 25°, and in anotherembodiment the cut angle is at least 30°. This creates a larger surfacearea 60. The distal end of deployable member 34 can also have these cutangles.

[0066] Referring to FIGS. 16 and 17, each or selected electrodes 18 anddeployable member 34 can have an associated spacer 62. Spacers 62 areadvanceable from distal end 14 of introducer 12 and can be coupled toadvancement member 30. Spacers 62 create a physical spacing thatseparates the deployed electrodes 18 from each other. The spacingcreated by spacers 62 also forms an area in tissue site 28 where thereis reduced or very little cell necrosis. Positioned within spacers 62 isan insulation 64 that electrically and electromagnetically isolateselectrodes 18 from spacers 62.

[0067] As illustrates in FIGS. 18 and 19, apparatus 10 can include aslidable member 66 that provides an electrical connection between energydelivery 16 and energy source 40. Slidable member 66 can be advancementmember 30 or a handpiece. In one embodiment, slidable member 66 has oneor two electrical contact pads 68 which can be resistor strips. Whenslidable member is moved in a distal direction relative to distal end 14of introducer 12 resistor strips 68 becomes engaged with a contact 70(FIG. 18). Contact 70 is coupled to energy delivery device 16. Whenresistor strips 68 are engaged with contact 70, power and energy isdelivered from energy source to electrodes 18. Slidable member 66 isthen moved in a distal direction and resistor strips become un-engagedwith contact 70 and the delivery of power from energy source 40 isdisrupted (FIG. 19). The employment of slidable member 66 provides aconvenient energy delivery device 16 on and off mechanism at the hand ofthe physician.

[0068] Resistor strips 68 can be used as sensors to recognize a variablesetting of one or all of electrodes 18 of energy delivery device 16.Resistor strips 68 can be used to measure resistance at a setting sothat a change in the resistance value can be measured as slidable member66 is moved and a corresponding change in the energy delivery surfacecorresponding to the electrodes 18. The resistance value can becorrelated to determine an optimal power in delivering energy fromenergy source 40. Gap sensors, including but not limited to lasers andultrasound, can be used to determine the variable setting.

[0069] Referring now to FIG. 20, a feedback control system 72 isconnected to energy source 40, sensors 36 and energy delivery device 16.Feedback control system 72 receives temperature or impedance data fromsensors 36 and the amount of electromagnetic energy received by energydelivery device 16 is modified from an initial setting of cell necrosisenergy output, cell necrosis time, temperature, and current density (the“Four Parameters”). Feedback control system 72 can automatically changeany of the Four Parameters. Feedback control system 72 can detectimpedance or temperature and change any of the Four Parameters. Feedbackcontrol system 72 can include a multiplexer to multiplex differentelectrodes 18 and a temperature detection circuit that provides acontrol signal representative of temperature or impedance detected atone or more sensors 36. A microprocessor can be connected to thetemperature control circuit.

[0070] The user of apparatus 10 can input an impedance value whichcorresponds to a setting position located at apparatus 10. Based on thisvalue, along with measured impedance values, feedback control system 72determines an optimal power and time need in the delivery of RF energy.Temperature is also sensed for monitoring and feedback purposes.Temperature can be maintained to a certain level by having feedbackcontrol system 72 adjust the power output automatically to maintain thatlevel.

[0071] In another embodiment, feedback control system 72 determines anoptimal power and time for a baseline setting. Ablation volumes orlesions are formed at the baseline first. Larger lesions can be obtainedby extending the time of ablation after a center core is formed at thebaseline. A completion of lesion creation can be checked by advancingenergy delivery device 16 from distal end 14 of introducer 12 to adesired lesion size and by monitoring the temperature at the peripheryof the lesion.

[0072] In another embodiment, feedback control system 72 is programmedso the delivery of energy to energy delivery device 16 is paused atcertain intervals at which time temperature is measured. By comparingmeasured temperatures to desired temperatures feedback control system 72can terminate or continue the delivery of power to electrodes 18 for anappropriate length of time.

[0073] The following discussion pertains particularly to the use of anRF energy source and RF electrodes but applies to other energy deliverydevices and energy sources including but not limited to microwave,ultrasound, resistive heating, coherent and incoherent light, and thelike.

[0074] Current delivered to electrodes 18 is measured by a currentsensor 74. Voltage is measured by voltage sensor 76. Impedance and powerare then calculated at power and impedance calculation device 78. Thesevalues can then be displayed at user interface and display 80. Signalsrepresentative of power and impedance values are received by controller82.

[0075] A control signal is generated by controller 82 that isproportional to the difference between an actual measured value, and adesired value. The control signal is used by power circuits 84 to adjustthe power output in an appropriate amount in order to maintain thedesired power delivered at energy delivery device 16.

[0076] In a similar manner, temperatures detected at sensors 36 providefeedback for determining the extent of cell necrosis, and when acompleted cell necrosis has reached the physical location of sensors 36.The actual temperatures are measured at temperature measurement device86 and the temperatures are displayed at user interface and display 80.A control signal is generated by controller 82 that is proportional tothe difference between an actual measured temperature, and a desiredtemperature. The control signal is used by power circuits 84 to adjustthe power output in an appropriate amount in order to maintain thedesired temperature delivered at the respective sensor 36. A multiplexercan be included to measure current, voltage and temperature, at thenumerous sensors 36, and energy is delivered to energy delivery device16. A variable electrode setting 88 is coupled to controller 82.

[0077] Controller 82 can be a digital or analog controller, or acomputer with software. When controller 82 is a computer it can includea CPU coupled through a system bus. On this system can be a keyboard, adisk drive, or other non-volatile memory systems, a display, and otherperipherals, as are known in the art. Also coupled to the bus are aprogram memory and a data memory.

[0078] User interface and display 80 includes operator controls and adisplay. Controller 82 can be coupled to imaging systems, including butnot limited to ultrasound, CT scanners, X-ray, MRI, mammographic X-rayand the like. Further, direct visualization and tactile imaging can beutilized.

[0079] The output of current sensor 74 and voltage sensor 76 is used bycontroller 82 to maintain a selected power level at energy deliverydevice 16. The amount of RF energy delivered controls the amount ofpower. A profile of power delivered can be incorporated in controller82, and a preset amount of energy to be delivered can also be profiled.

[0080] Circuitry, software and feedback to controller 82 result inprocess control, and the maintenance of the selected power, and are usedto change, (i) the selected power, including RF, microwave, laser andthe like, (ii) the duty cycle (on-off and wattage), (iii) bi-polar ormono-polar energy delivery and (iv) infusion medium delivery, includingflow rate and pressure. These process variables are controlled andvaried, while maintaining the desired delivery of power independent ofchanges in voltage or current, based on temperatures monitored atsensors 36.

[0081] Referring now to FIG. 21, current sensor 74 and voltage sensor 76are connected to the input of an analog amplifier 90. Analog amplifier90 can be a conventional differential amplifier circuit for use withsensors 36. The output of analog amplifier 90 is sequentially connectedby an analog multiplexer 46 to the input of A/D converter 92. The outputof analog amplifier 90 is a voltage which represents the respectivesensed temperatures. Digitized amplifier output voltages are supplied byA/D converter 92 to a microprocessor 96. Microprocessor 96 may be ModelNo. 68HCII available from Motorola. However, it will be appreciated thatany suitable microprocessor or general purpose digital or analogcomputer can be used to calculate impedance or temperature.

[0082] Microprocessor 96 sequentially receives and stores digitalrepresentations of impedance and temperature. Each digital valuereceived by microprocessor 96 corresponds to different temperatures andimpedances.

[0083] Calculated power and impedance values can be indicated on userinterface and display 80. Alternatively, or in addition to the numericalindication of power or impedance, calculated impedance and power valuescan be compared by microprocessor 96 with power and impedance limits.When the values exceed predetermined power or impedance values, awarning can be given on user interface and display 80, and additionally,the delivery of RF energy can be reduced, modified or interrupted. Acontrol signal from microprocessor 96 can modify the power levelsupplied by energy source 40.

[0084] The foregoing description of a preferred embodiment of theinvention has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Obviously, many modificationsand variations will be apparent to practitioners skilled in this art. Itis intended that the scope of the invention be defined by the followingclaims and their equivalents.

What is claimed is:
 1. A cell necrosis apparatus, comprising: an introducer with a proximal end and a distal end; an energy delivery device including a plurality of electrodes each electrode having a tissue piercing distal end and positionable in the introducer as the introducer is advanced through tissue, at least one electrode of the plurality of electrodes being deployable with curvature from the introducer; and a slidable sensing member positionable within the introducer or a handpiece coupled to the introducer and electrically coupled to the energy delivery device, the sensing member configured to measure a property of the energy delivery device or at least one electrode of the plurality of electrodes.
 2. The apparatus of claim 1 , wherein the introducer distal end is sufficiently sharp to penetrate tissue.
 3. The apparatus of claim 1 , wherein at least one electrode of the plurality of electrodes is an RF electrode.
 4. The apparatus of claim 1 , wherein the sensing member is configured to measure a deployed length of one of the energy delivery device or at least one electrode of the plurality of electrodes.
 5. The apparatus of claim 1 , wherein the sensing member is configured to measure a deployed area of one of the energy delivery device or at least one electrode of the plurality of electrodes.
 6. The apparatus of claim 1 , wherein the sensing member is configured to measure an area of an energy delivery surface of one of the energy delivery device or at lease one electrode of the plurality of electrodes.
 7. The apparatus of claim 1 , wherein the sensing member is configured to be coupled to an energy source.
 8. The apparatus of claim 6 , wherein the energy source is one of an electrical energy source, an RF energy source, a microwave energy source or an optical source.
 9. The apparatus of claim 1 , wherein the sensing member includes a resistive element, the apparatus further comprising: a contact member coupled to the energy delivery device, the contact member configured to engage the resistive element and establish an electrical circuit between the resistive element and an energy source configured to be coupled to the energy delivery.
 10. The apparatus of claim 8 , wherein the resistive element is a resistive strip.
 11. The apparatus of claim 9 , wherein the contact member is configured to mechanically or slidably engage the resistor strip.
 12. The apparatus of claim 9 , wherein the resistor strip is configured to measure a deployed area of one of the energy delivery device or at least one electrode of the plurality of electrodes.
 13. The apparatus of claim 9 , wherein the resistor strip is configured to measure an area of an energy delivery surface of one of the energy delivery device or at lease one electrode of the plurality of electrodes.
 14. The apparatus of claim 9 , wherein the resistor strip is configured to be coupled to one of an energy source, an electrical energy source, an RF energy source, a microwave energy source or an optical source.
 15. The apparatus of claim 9 , wherein the resistor strip includes a first and a second resistor strip.
 16. The apparatus of claim 14 , wherein a first strip resistance is less than a second strip resistance.
 17. The apparatus of claim 14 , wherein the contact member is configured to engage at least one of the first or the second resistance strips.
 18. The apparatus of claim 9 , wherein the resistor strip is configured to detect a variable setting of at least one electrode of the plurality of electrodes.
 19. The apparatus of claim 9 , wherein the resistive strip is configured to measure an electrical resistance responsive to movement of at least one of the energy delivery device or at least one electrode of the first and second set of electrodes.
 20. The apparatus of claim 18 , wherein the electrical resistance is utilized to optimize a delivery of power to at least one electrode of the plurality of electrodes by a power supply coupled to the energy delivery device.
 21. The apparatus of claim 1 , wherein the sensing member includes one of a gap sensor, an ultrasonic transducer or an optical sensor.
 22. The apparatus of claim 1 , wherein the sensing member is configured to control the delivery of power to the energy delivery device from a power source configured to be coupled to the energy delivery device.
 23. The apparatus of claim 21 , wherein the sensing member is configured to optimize the delivery of power to the energy delivery device.
 24. The apparatus of claim 21 , wherein the sensing member is configured to control the delivery of power to the energy delivery device responsive to an amount of deployment of the energy delivery device or an electrode of the plurality of electrodes.
 25. The apparatus of claim 23 , wherein the deployment is in one of a linear, a radial or a curvilinear direction with respect to a longitudinal axis of the introducer.
 26. The apparatus of claim 21 , the sensing member is configured to provide on off control of power to the energy delivery device.
 27. The apparatus of claim 1 , wherein the sensing member is at least partially positioned within a handpiece coupled to the proximal end of the introducer.
 28. The apparatus of claim 1 , wherein the sensing member is an electrode advancement member coupled to the energy delivery device.
 29. The apparatus of claim 1 , wherein the plurality of electrodes includes a first and second set of electrodes, deployed portions of the electrodes of the first and second sets of electrodes being configured to create substantially the same geometric ablation shape at a first deployed position and a second deployed position.
 30. The apparatus of claim 28 , wherein at least one electrode of the first or second sets of electrodes is an RF electrode.
 31. The apparatus of claim 28 , wherein the sensing member is configured to measure a deployed length of one of the energy delivery device or at least one electrode of the first or second sets of electrodes of electrodes.
 32. The apparatus of claim 28 , wherein the sensing member is configured to measure a deployed area of one of the energy delivery device or at least one electrode of the first or second sets of electrodes of electrodes.
 33. The apparatus of claim 28 , wherein the sensing member is configured to measure an area of an energy delivery surface of one of the energy delivery device or at lease one electrode of the first or second sets of electrodes of electrodes.
 34. The apparatus of claim 28 , wherein the sensing member is configured to be coupled to an energy source.
 35. The apparatus of claim 33 , wherein the energy source is one of an electrical energy source, an RF energy source, a microwave energy source or an optical source.
 36. The apparatus of claim 28 , wherein the sensing member includes a resistive element, the apparatus further comprising: a contact member coupled to the energy delivery device, the contact member configured to engage the resistive element and establish an electrical circuit between the resistive element and an energy source configured to be coupled to the energy delivery.
 37. The apparatus of claim 35 , wherein the resistive element is a resistive strip.
 38. The apparatus of claim 36 , wherein the contact member is configured to mechanically or slidably engage the resistor strip.
 39. The apparatus of claim 36 , wherein the resistor strip is configured to measure a deployed area of one of the energy delivery device or at least one electrode of the first or second sets of electrodes of electrodes.
 40. The apparatus of claim 36 , wherein the resistor strip is configured to measure an area of an energy delivery surface of one of the energy delivery device or at lease one electrode of the first or second sets of electrodes of electrodes.
 41. The apparatus of claim 36 , wherein the resistor strip is configured to be coupled to one of an energy source, an electrical energy source, an RF energy source, a microwave energy source or an optical source.
 42. The apparatus of claim 36 , wherein the resistor strip includes a first and a second resistor strip.
 43. The apparatus of claim 41 , wherein a first strip resistance is less than a second strip resistance.
 44. The apparatus of claim 41 , wherein the contact member is configured to engage at least one of the first or the second resistance strips.
 45. The apparatus of claim 36 , wherein the resistor strip is configured to detect a variable setting of at least one electrode of the first or second sets of electrodes of electrodes.
 46. The apparatus of claim 36 , wherein the resistive strip is configured to measure an electrical resistance responsive to movement of at least one of the energy delivery device or at least one electrode of the first or second set of electrodes.
 47. The apparatus of claim 45 , wherein the electrical resistance is utilized to optimize a delivery of power to at least one electrode of the plurality of electrodes by a power supply coupled to the energy delivery device.
 48. The apparatus of claim 28 , wherein the sensing member includes one of a gap sensor, an ultrasonic transducer or an optical sensor.
 49. The apparatus of claim 28 , wherein the sensing member is configured to control the delivery of power to the energy delivery device from a power source configured to be coupled to the energy delivery device.
 50. The apparatus of claim 48 , wherein the sensing member is configured to optimize the delivery of power to the energy delivery device.
 51. The apparatus of claim 48 , wherein the sensing member is configured to control the delivery of power to the energy delivery device responsive to an amount of deployment of the energy delivery device or an electrode of the plurality of electrodes.
 52. The apparatus of claim 50 , wherein the deployment is in one of a linear, a radial or a curvilinear direction with respect to a longitudinal axis of the introducer.
 53. The apparatus of claim 48 , the sensing member is configured to provide on off control of power to the energy delivery device.
 54. The apparatus of claim 28 , wherein the sensing member is at least partially positioned within a handpiece coupled to a proximal end of the introducer.
 55. The apparatus of claim 28 , wherein the sensing member is an electrode advancement member coupled to the energy delivery device.
 56. A cell necrosis apparatus, comprising: an introducer with a distal end positionable in tissue; an energy delivery device including a plurality of electrodes each electrode having a tissue piercing distal end and positionable in the introducer as the introducer is advanced through tissue, at least one electrode of the plurality of electrodes being deployable with curvature from the introducer; and a movable sensing member positionable within the introducer and electrically coupled to the energy delivery device, the sensing member configured to measure a property of the energy delivery device or at least one electrode of the plurality of electrodes.
 57. A cell necrosis apparatus, comprising: an introducer means with a distal end positionable in tissue; an energy delivery device means including a plurality of electrodes means each electrode means having a tissue piercing distal end and positionable in the introducer means as the introducer means is advanced through tissue, at least one electrode means of the plurality of electrodes means being deployable with curvature from the introducer means; and a slidable sensing means positionable within the introducer means and electrically coupled to the energy delivery device means, the sensing means configured to measure a property of the energy delivery device means or at least one electrode means of the plurality of electrodes means.
 58. A tissue treatment method, comprising: providing an cell necrosis apparatus including an introducer with a distal end adapted to be positionale in tissue; an energy delivery device including a plurality of electrodes and a slidable sensing member, each electrode of the plurality of electrode having a tissue piercing distal end and positionable in the introducer as the introducer is advanced through tissue, at least one electrode of the plurality of electrodes being deployable with curvature from the introducer; the sensing member being electrically coupled to the energy delivery device; positioning the introducer within a target tissue site; deploying at least one electrode of the plurality of electrodes into tumor mass; utilzing the sensing member to determine a characteristic of at least one electrode of the plurality of electrodes; and delivering energy from the energy delivery device to the tumor mass.
 59. The method of claim 57 , wherein at least one electrode of the plurality of electrodes is an RF electrode.
 60. The method of claim 57 , wherein the characteristic is at least one of a deployed length, a deployed area or an energy delivery surface area.
 61. The method of claim 57 , wherein the introducer includes a handpiece, the sensing member being at least partially positionable within the handpiece.
 62. The method of claim 60 , further comprising: manipulating the handpiece.
 63. The method of claim 61 , further comprising: manipulating the handpiece to deploy, advance or position at least one electrode of the plurality of electrodes.
 64. The method of claim 57 , further comprising: controlling a delivery of power to at least one electrode of the plurality of electrodes member from a coupled power supply utilizing the sensing member.
 65. The method of claim 57 , further comprising: measuring an electrical resistance responsive to movement of at least one of the energy delivery device or at least one electrode of the first and second set of electrodes.
 66. The method of claim 64 , further comprising: controlling a delivery of power to at least one electrode of the plurality of electrodes from a coupled power supply responsive to the electrical resistance.
 67. The method of claim 64 , further comprising: optimizing a delivery of power to at least one electrode of the plurality of electrodes from a coupled power supply responsive to the electrical resistance.
 68. The method of claim 57 , further comprising: utilizing the sensing member to identify a cell necrosis apparatus. 